Vessel sealing instrument

ABSTRACT

A bipolar electrosurgical instrument includes first and second shafts each having a jaw member extending from its distal end. Each jaw member is adapted to connect to a source of electrosurgical energy such that the jaw members are capable of selectively conducting energy through tissue held therebetween. A knife channel is configured to reciprocate a cutting mechanism therealong. An actuator selectively advances the cutting mechanism. A switch is disposed on the first shaft and is configured to be depressed between a first position and at least one subsequent position upon biasing engagement with a mechanical interface disposed on the second shaft. The first position of the switch relays information to the user corresponding to a desired pressure on tissue and the at least one subsequent position is configured to activate the source of electrosurgical energy to supply electrosurgical energy to the jaw members.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/269,660, filed on Feb. 7, 2019, which is a continuation ofU.S. patent application Ser. No. 15/791,552, filed on Oct. 24, 2017, nowU.S. Pat. No. 10,201,384, which is a continuation of U.S. patentapplication Ser. No. 15/018,985, filed on Feb. 9, 2016, now U.S. Pat.No. 9,795,439, which is a continuation of U.S. patent application Ser.No. 14/795,246, filed on Jul. 9, 2015, now U.S. Pat. No. 9,498,279,which is a continuation of U.S. patent application Ser. No. 12/897,346,filed on Oct. 4, 2010, now U.S. Pat. No. 9,655,672.

INTRODUCTION

The present disclosure relates to forceps used for open surgicalprocedures. More particularly, the present disclosure relates to aforceps that applies electrosurgical current to seal tissue.

BACKGROUND

A hemostat or forceps is a simple plier-like tool which uses mechanicalaction between its jaws to constrict vessels and is commonly used inopen surgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue.

Certain surgical procedures require sealing and cutting blood vessels orvascular tissue. Several journal articles have disclosed methods forsealing small blood vessels using electrosurgery. An article entitledStudies on Coagulation and the Development of an Automatic ComputerizedBipolar Coagulator, J. Neurosurg., Volume 75, July 1991, describes abipolar coagulator which is used to seal small blood vessels. Thearticle states that it is not possible to safely coagulate arteries witha diameter larger than 2 to 2.5 mm. A second article is entitledAutomatically Controlled Bipolar Electrocoagulation—“COA-COMP”,Neurosurg. Rev. (1984), pp. 187-190, describes a method for terminatingelectrosurgical power to the vessel so that charring of the vessel wallscan be avoided.

By utilizing an electrosurgical forceps, a surgeon can either cauterize,coagulate/desiccate, reduce or slow bleeding and/or seal vessels bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied to the tissue. Generally, the electrical configuration ofelectrosurgical forceps can be categorized in two classifications: 1)monopolar electrosurgical forceps; and 2) bipolar electrosurgicalforceps.

Monopolar forceps utilize one active electrode associated with theclamping end effector and a remote patient return electrode or pad whichis typically attached externally to the patient. When theelectrosurgical energy is applied, the energy travels from the activeelectrode, to the surgical site, through the patient and to the returnelectrode.

Bipolar electrosurgical forceps utilize two generally opposingelectrodes which are disposed on the inner opposing surfaces of the endeffectors and which are both electrically coupled to an electrosurgicalgenerator. Each electrode is charged to a different electric potential.Since tissue is a conductor of electrical energy, when the effectors areutilized to grasp tissue therebetween, the electrical energy can beselectively transferred through the tissue.

In order to effect a proper seal with larger vessels, two predominantmechanical parameters must be accurately controlled—the pressure appliedto the vessel and the gap between the electrodes both of which affectthickness of the sealed vessel. More particularly, accurate applicationof the pressure is important to oppose the walls of the vessel, toreduce the tissue impedance to a low enough value that allows enoughelectrosurgical energy through the tissue, to overcome the forces ofexpansion during tissue heating and to contribute to the end tissuethickness which is an indication of a good seal. It has been determinedthat a fused vessel wall is optimum between 0.001 and 0.006 inches.Below this range, the seal may shred or tear and above this range thelumens may not be properly or effectively sealed.

With respect to smaller vessel, the pressure applied to the tissue tendsto become less relevant whereas the gap distance between theelectrically conductive surfaces becomes more significant for effectivesealing. In other words, the chances of the two electrically conductivesurfaces touching during activation increases as the vessels becomesmaller.

Electrosurgical methods may be able to seal larger vessels using anappropriate electrosurgical power curve, coupled with an instrumentcapable of applying a large closure force to the vessel walls. It isthought that the process of coagulating small vessels is fundamentallydifferent than electrosurgical vessel sealing. For the purposes herein,“coagulation” is defined as a process of desiccating tissue wherein thetissue cells are ruptured and dried and vessel sealing is defined as theprocess of liquefying the collagen in the tissue so that it reforms intoa fused mass. Thus, coagulation of small vessels is sufficient topermanently close them. Larger vessels need to be sealed to assurepermanent closure.

Numerous bipolar electrosurgical forceps have been proposed in the pastfor various open surgical procedures. However, some of these designs maynot provide uniformly reproducible pressure to the blood vessel and mayresult in an ineffective or non-uniform seal. For example, U.S. Pat. No.2,176,479 to Willis, U.S. Pat. Nos. 4,005,714 and 4,031,898 toHiltebrandt, U.S. Pat. Nos. 5,827,274, 5,290,287 and 5,312,433 to Boebelet al., U.S. Pat. Nos. 4,370,980, 4,552,143, 5,026,370 and 5,116,332 toLottick, U.S. Pat. No. 5,443,463 to Stern et al., U.S. Pat. No.5,484,436 to Eggers et al. and U.S. Pat. No. 5,951,549 to Richardson etal., all relate to electrosurgical instruments for coagulating, cuttingand/or sealing vessels or tissue.

Many of these instruments include blade members or shearing memberswhich simply cut tissue in a mechanical and/or electromechanical mannerand are relatively ineffective for vessel sealing purposes. Otherinstruments rely on clamping pressure alone to procure proper sealingthickness and are not designed to take into account gap tolerancesand/or parallelism and flatness requirements which are parameters which,if properly controlled, can assure a consistent and effective tissueseal. For example, it is known that it is difficult to adequatelycontrol thickness of the resulting sealed tissue by controlling clampingpressure alone for either of two reasons: 1) if too much force isapplied, there is a possibility that the two poles will touch and energywill not be transferred through the tissue resulting in an ineffectiveseal; or 2) if too low a force is applied, a thicker less reliable sealis created.

SUMMARY

According to an embodiment of the present disclosure, a bipolarelectrosurgical instrument includes first and second shafts each havinga jaw member extending from its distal end and a handle disposed at itsproximal end for effecting movement of the jaw members relative to oneanother about a pivot from a first position wherein the jaw members aredisposed in spaced relation relative to one another to a second positionwherein the jaw members cooperate to grasp tissue. Each jaw member isadapted to connect to a source of electrosurgical energy such that thejaw members are capable of selectively conducting energy through tissueheld therebetween to effect a tissue seal. At least one of the jawmembers includes a knife channel defined along its length. The knifechannel is configured to reciprocate a cutting mechanism therealong tocut tissue grasped between the jaw members. The instrument also includesan actuator for selectively advancing the cutting mechanism from a firstposition wherein the cutting mechanism is disposed proximal to tissuegrasped between the jaw members to at least one subsequent positionwherein the cutting mechanism is disposed distal to tissue graspedbetween the jaw members. The instrument also includes a switch disposedon the first shaft. The switch is configured to be depressed between afirst position and at least one subsequent position upon biasingengagement with a mechanical interface disposed on the second shaft uponmovement of the jaw members from the first position to the secondposition. The first position of the switch relays information to theuser corresponding to a desired pressure on tissue grasped between thejaw members and the at least one subsequent position is configured toactivate the source of electrosurgical energy to supply electrosurgicalenergy to the jaw members.

According to another embodiment of the present disclosure, a bipolarelectrosurgical instrument includes first and second shafts each havinga jaw member extending from its distal end and a handle disposed at itsproximal end for effecting movement of the jaw members relative to oneanother about a pivot from a first position wherein the jaw members aredisposed in spaced relation relative to one another to a second positionwherein the jaw members cooperate to grasp tissue. Each jaw member isadapted to connect to a source of electrosurgical energy such that thejaw members are capable of selectively conducting energy through tissueheld therebetween to effect a tissue seal. A knife channel is definedalong a length of one or both of the jaw members. The knife channel isconfigured to reciprocate a cutting mechanism therealong to cut tissuegrasped between the jaw members. The instrument also includes anactuator for selectively advancing the cutting mechanism from a firstposition wherein the cutting mechanism is disposed proximal to tissuegrasped between the jaw members to at least one subsequent positionwherein the cutting mechanism is disposed distal to tissue graspedbetween the jaw members. The instrument also includes a switch disposedon the first shaft. The switch is configured to be depressed between atleast two positions upon biasing engagement with the second shaft uponmovement of the jaw members from the first position to the secondposition. The switch generates a first tactile response upon movement tothe first position of the switch and a subsequent tactile response uponmovement to the at least one subsequent position of the switch. Thefirst tactile response relays information to the user corresponding to apredetermined pressure on tissue grasped between the jaw members and thesubsequent tactile response is configured to activate the source ofelectrosurgical energy to supply electrosurgical energy to the jawmembers.

According to another embodiment of the present disclosure, a method ofperforming an electrosurgical procedure includes the step ofapproximating first and second shafts of a bipolar forceps to grasptissue between first and second jaw members associated with the firstand second shafts. The method also includes the steps of depressing aswitch upon approximation of the first and second shafts to a firstposition to relay information to the user corresponding to apredetermined grasping pressure applied to tissue grasped between thejaw members and depressing the switch to at least one subsequentposition to activate a source of electrosurgical energy to supplyelectrosurgical energy to the jaw members.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a right, perspective view of a forceps according to oneembodiment of the present disclosure;

FIG. 2 is an exploded view of the forceps of FIG. 1;

FIG. 3A is an exploded view of an end effector assembly of the forcepsof FIG. 1;

FIG. 3B is a cross-sectional view of the end effector assembly of theforceps of FIG. 1;

FIG. 4A is a side view of the forceps of FIG. 1 with parts partiallyremoved to show the electrical connection between a switch and the endeffector assembly;

FIG. 4B is a left, perspective view of a jaw member of the end effectorassembly of FIG. 1;

FIG. 4C is a left, perspective view of a jaw member of the end effectorassembly of FIG. 1; and

FIGS. 5A-5C are side views of the forceps of FIG. 1 illustratingactuation thereof between open and closed positions; and

FIG. 6 is a side view of a knife for use with the forceps of FIG. 1according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring initially to FIGS. 1 and 2, a forceps 10 for use with opensurgical procedures includes elongated shaft portions 12 a and 12 b eachhaving a proximal end 14 a, 14 b and a distal end 16 a and 16 b,respectively. In the drawings and in the description that follows, theterm “proximal”, as is traditional, will refer to the end of the forceps10 that is closer to the user, while the term “distal” will refer to theend that is further from the user.

The forceps 10 includes an end effector assembly 100 that attaches tothe distal ends 16 a and 16 b of shafts 12 a and 12 b, respectively. Theend effector assembly 100 includes pair of opposing jaw members 110 and120 that are pivotably connected and movable relative to one anotherabout a pivot 65 (FIG. 2) to grasp tissue. Pivot 65 is disposed on aproximal end of jaw member 120 and includes opposing halves 65 a and 65b disposed on opposing sides of a channel 126 (FIG. 4C) that isconfigured to facilitate reciprocation of a cutting mechanism or knife85 therethrough (FIG. 2), as discussed in detail below.

Each shaft 12 a and 12 b includes a handle 15 and 17, respectively,disposed at the proximal end 14 a and 14 b thereof. Each handle 15 and17 defines a finger hole 15 a and 17 a, respectively, therethrough forreceiving a finger of the user. Handles 15 and 17 facilitate movement ofthe shafts 12 a and 12 b relative to one another which, in turn, pivotthe jaw members 110 and 120 from an open position wherein the jawmembers 110 and 120 are disposed in spaced relation relative to oneanother to a clamping or closed position wherein the jaw members 110 and120 cooperate to grasp tissue therebetween.

As best seen in FIG. 2, shaft 12 a is constructed from two components,namely, 12 a 1 and 12 a 2, that are coupled together to form shaft 12 a.Likewise, shaft 12 b is constructed from two components, namely, 12 b 1and 12 b 2, that are coupled together to form shaft 12 b. In someembodiments, component halves 12 a 1 and 12 a 2 and component halves 12b 1 and 12 b 2 are ultrasonically welded together at a plurality ofdifferent weld points and/or may be mechanically coupled together by anysuitable method including snap-fitting, adhesive, fastened, etc.

The arrangement of shaft 12 b is slightly different from shaft 12 a.More particularly, shaft 12 a is generally hollow to house the knife 85and an actuating mechanism 40. The actuating mechanism 40 is operativelyassociated with a trigger 45 having handle members 45 a and 45 bdisposed on opposing sides of shaft 12 a to facilitate left-handed andright-handed operation of trigger 45. Trigger 45 is operativelyassociated with a series of suitable inter-cooperating elements (e.g.,FIG. 2 shows a trigger link 43, a knife pushing link 41, a spring 49,and an anti-deployment link 47) configured to mechanically cooperate(not explicitly shown) to actuate the knife 85 through tissue graspedbetween jaw members 110 and 120 upon actuation of trigger 45. Handlemembers 45 a and 45 b operate in identical fashion such that use ofeither of handle members 45 a and 45 b operates the trigger 45 toreciprocate the knife 85 through the knife channel 115 (FIG. 5C).Further, the proximal end 14 b of shaft 12 b includes a switch cavity 13protruding from an inner facing surface 23 b of shaft 12 b andconfigured to seat a depressible switch 50 therein (and the electricalcomponents associated therewith). Switch 50 aligns with an opposinginner facing surface 23 a of the proximal end 14 a of shaft 12 a suchthat upon approximation of shafts 12 a and 12 b toward one another, theswitch 50 is depressed into biasing engagement with the opposing innerfacing surface 23 a of the proximal end 14 a of shaft 12 a.

As shown in FIG. 1, an electrosurgical cable 210 having a plug 200 atits proximal end connects the forceps 10 to an electrosurgical generator(not shown). More specifically, the distal end of the cable 210 issecurely held to the shaft 12 b by a proximal shaft connector 19 and theproximal end of the cable 210 includes a plug 200 having prongs 202 a,202 b, and 202 c that are configured to electrically and mechanicallyengage the electrosurgical generator.

The tissue grasping portions of the jaw members 110 and 120 aregenerally symmetrical and include similar component features thatcooperate to permit facile rotation about pivot 65 to effect thegrasping and sealing of tissue. As a result, and unless otherwise noted,jaw member 110 and the operative features associated therewith areinitially described herein in detail and the similar component featureswith respect to jaw member 120 will be briefly summarized thereafter.

With reference to FIGS. 3A and 3B, jaw member 110 includes an outerhousing 116 a, first and second non-conductive plastic insulators 108 aand 114 a, and an electrically conductive sealing surface 112 a. Thefirst and second insulators 108 a and 114 a are overmolded about jawhousing 116 a in a two-shot overmolding process. More specifically, thefirst insulator 108 a is overmolded about jaw housing 116 a toelectrically insulate the jaw housing 116 a from sealing surface 112 aand the second insulator 114 a is overmolded about jaw housing 116 a tosecure the electrically conductive sealing surface 112 a thereto. Thismay be accomplished by stamping, by overmolding, by overmolding astamped sealing surface, and/or by overmolding a metal injection moldedsealing surface. The jaw members 110 and 120 are made from a conductivematerial. In some embodiments, the jaw members 110 and 120 are powdercoated with an insulative coating to reduce stray current concentrationsduring sealing.

As best shown by the cross-sectional view of FIG. 3B, electricallyconductive sealing surface 112 a of jaw member 110 is pronounced fromthe jaw housing 116 a and the second insulator 114 a such that tissue isgrasped by the opposing electrically conductive sealing surfaces 112 aand 112 b when jaw members 110 and 120 are in the closed position.

Likewise, jaw member 120 includes similar elements that correspond tojaw member 110 including: an outer housing 116 b, first and secondplastic insulators 108 b and 114 b, and an electrically conductivesealing surface 112 b that is pronounced from the jaw housing 116 b andsecond insulator 114 b. As described above with respect to jaw member110, the first insulator 108 b electrically insulates the jaw housing116 b from the sealing surface 112 b and the second insulator 114 bsecures the sealing surface 112 b to the jaw housing 116 b. Insulators114 a and 114 b extend along the entire length of jaw members 110 and120, respectively, to reduce alternate or stray current paths duringsealing. In some embodiments, each of sealing surfaces 112 a and 112 bmay include an outer peripheral edge that has a radius such that eachinsulator 114 a and 114 b meets the respective sealing surface 112 a and112 b along an adjoining edge that is generally tangential to the radiusand/or meets along the radius.

As shown in FIGS. 3A and 3B, at least one of the jaw members, e.g., jawmember 120, includes at least one stop member 750 disposed on the innerfacing surfaces of the electrically conductive sealing surface 112 band/or 112 a. Alternatively or in addition, the stop member(s) 750 maybe disposed adjacent to the electrically conductive sealing surfaces 112a, 112 b or proximate the pivot 65. The stop member(s) 750 facilitategripping and manipulation of tissue and to define a gap between opposingjaw members 110 and 120 during sealing and cutting of tissue. In someembodiments, the stop member(s) 750 maintain a gap distance betweenopposing jaw members 110 and 120 within a range of about 0.001 inches(˜0.03 millimeters) to about 0.006 inches (˜0.015 millimeters).

As shown in FIG. 2, shaft 12 b includes a beam 57 disposed therein andextending between handle 15 and jaw member 110. In some embodiments, thebeam 57 is constructed of flexible steel to allow the user to generateadditional sealing pressure on tissue grasped between the jaw members110 and 120. More specifically, once end effector assembly 100 is closedabout tissue, the shafts 12 a and 12 b may be squeezed toward each otherto utilize the flexibility of the beam 57 to generate the necessaryclosure pressure between jaw members 110 and 120. In this scenario, themechanical advantage realized by the compressive force associated withthe beam 57 facilitates and assures consistent, uniform, and accurateclosure pressure about tissue grasped between jaw members 110 and 120(e.g., within a working pressure range of about 3 kg/cm2 to about 16kg/cm2). By controlling the intensity, frequency, and duration of theelectrosurgical energy applied to the tissue, the user can seal tissue.In some embodiments, the gap distance between opposing sealing surfaces112 a and 112 b during sealing ranges from about 0.001 inches to about0.005 inches.

In some embodiments, the sealing surfaces 112 a and 112 b are relativelyflat to avoid current concentrations at sharp edges and to avoid arcingbetween high points. In addition, and due to the reaction force of thetissue when engaged, each of jaw members 110 and 120 may be manufacturedto resist bending, e.g., tapered along its length to provide a constantpressure for a constant tissue thickness at parallel and the thickerproximal portion of the jaw members 110 and 120 will resist bending dueto the reaction force of the tissue.

As shown in FIGS. 3A, 3B, 4B, and 4C, at least one of jaw members 110and 120 includes a knife channel 115 a and/or 115 b, respectively,disposed therebetween that is configured to allow reciprocation of aknife 85 therethrough. In the illustrated embodiment, a complete knifechannel 115 is formed when two opposing channel halves 115 a and 115 bassociated with respective jaw members 110 and 120 come together upongrasping of the tissue. Each plastic insulator 108 a and 108 b includesa trough 121 a and 121 b, respectively, that aligns in verticalregistration with an opposing knife channel half 115 a and 115 b,respectively, such that knife 85 does not contact or cut through plasticinsulators 108 a and 108 b upon reciprocation through knife channel 115.In some embodiments, the width of knife channels 115 a and 115 b andtheir respective troughs 121 a and 121 b may be equal along an entirelength thereof.

As best shown in FIG. 4A, the interior of cable 210 houses leads 71 a,71 b and 71 c. Leads 71 a, 71 b, and 71 c extend from the plug 200through cable 210 and exit the distal end of the cable 210 within theproximal connector 19 of shaft 12 b. More specifically, lead 71 a isinterconnected between prong 202 b and a first terminal 75 a of theswitch 50. Lead 71 b is interconnected between prong 202 c and a soldersleeve 73 a which, in turn, connects lead 71 b to an RF lead 71 d and toa second terminal 75 b of the switch 50 via a connector lead 71 f. RFlead 71 d carries a first electrical potential of electrosurgical energyfrom lead 71 b to sealing surface 112 a. Lead 71 c is interconnectedbetween prong 202 a and a solder sleeve 73 b which, in turn, connectslead 71 c to an RF lead 71 e. RF lead 71 e carries a second electricalpotential of electrosurgical energy from lead 71 c to sealing surface112 b.

With reference to FIG. 4B, a lead channel 77 is defined in the proximalend of jaw member 110 to provide a pathway for lead 71 d to connect to ajunction 311 a (FIG. 3A) extending from a proximal end of sealingsurface 112 a. A proximal end of lead channel 77 opens into a raceway 70that includes a generally elongated configuration with a narrowedproximal end 72 and a broadened distal end 74 that defines an arcuatesidewall 68. Lead 71 d is routed to follow a path through the proximalend 72 of raceway 70 and, further, through lead channel 77 forconnection to junction 311 a.

With reference to FIG. 4C, pivot halves 65 a and 65 b are disposed onopposing sides of channel 126 to facilitate translation of the knife 85therethrough (FIGS. 5A-5C). Pivot halves 65 a and 65 b are disposed in asplit spherical configuration and each include a respective base portion165 a and 165 b that support an extension portion 166 a and 166 bthereon, respectively. Extension portions 166 a and 166 b are configuredto engage correspondingly-dimensioned apertures 67 a and 67 b,respectively, disposed through pivot plate 66 to pivotably secure jawmember 110 to jaw member 120. A lead channel 109 is defined in theproximal end of jaw member 120 to provide a pathway for lead 71 e toconnect to a junction 311 b extending from a proximal end of sealingsurface 112 b. Lead 71 e is routed to follow a path through raceway 70and, further between opposing pivot halves 65 a and 65 b and throughlead channel 109 for connection to junction 311 b.

With reference to FIGS. 5A-5C, as the user applies closure pressure onshafts 12 a and 12 b to depress switch 50 (FIG. 5B), a first thresholdis met corresponding to the closure force applied to switch 50 as afunction of displacement of switch 50 that causes switch 50 to generatea first tactile response that corresponds to a complete grasping oftissue disposed between jaw members 110 and 120. Following the firsttactile response, as the user applies additional closure pressure onshafts 12 a and 12 b (FIG. 5C), a second threshold is met correspondingthe closure force applied to switch 50 as a function of displacement ofswitch 50 that causes the switch 50 to generate a second tactileresponse that corresponds to a signal being generated to theelectrosurgical generator to supply electrosurgical energy to thesealing surfaces 112 a and 112 b. More specifically, the second tactileresponse indicates closing of a normally open circuit between switchterminals 75 a and 75 b and, in turn, establishment of an electricalconnection between leads 71 a and 71 b. As a result of the electricalconnection between leads 71 a and 71 b, the electrosurgical generatorsenses a voltage drop between prongs 202 b and 202 c and, in responsethereto, supplies electrosurgical energy to sealing surfaces 112 a and112 b via leads 71 d and 71 e, respectively.

In one embodiment, the first tactile response indicates to the user thatthe maximum grasping pressure has been reached before end effector 100is energized where the user is free to approximate, manipulate, andgrasp tissue as needed. In this scenario, the second tactile responseindicates to the user the electrosurgical activation of the end effector100. The switch 50 may include a plurality of other tactile responsesbetween the above discussed first and second tactile responses and/orsubsequent to the second tactile response that correspond to particularfunctions of the forceps 10 such as, for example, operation of the knife85 and/or the actuation assembly 40, operation of a safety lockoutmechanism associated with the actuation assembly 40, as discussed indetail below.

As shown in FIG. 4A, forceps 10 may include a gauge or sensor element 87disposed within one or both of shafts 12 a, 12 b such that the clampingor grasping forces being applied to target tissue by end effector 100may be measured and/or detected. For example, in some embodiments,sensor element 87 may be a strain gauge 87 operably associated with oneor both jaw members 110, 120. Sensor element 87 may be one or more Halleffect sensors or strain gauges such as, for example, metallic straingauges, piezoresistive strain gauges, that may be disposed within one orboth of shafts 12 a and 12 b and/or within one or both of jaw members110 and 120 to detect tissue pressure. Metallic strain gauges operate onthe principle that as the geometry (e.g., length, width, thickness,etc.) of the conductive material changes due to mechanical stress, theresistance of the conductive material changes as a function thereof.This change in resistance is utilized to detect strain or appliedmechanical stress such as, for example, the mechanical stress applied totissue by jaw members 110 and 120. Piezoresistive strain gauges operatebased on the changing resistivity of a semiconductor due to theapplication of mechanical stress.

Hall effect sensors may be incorporated to determine the gap between jawmembers 110 and 120 based on a detected relationship between themagnetic field strength between jaw members 110 and 120 and the distancebetween jaw members 110 and 120.

In some embodiments, one or more reed switches 81 a, 81 b may beincorporated within shafts 12 a and 12 b to determine the proximitythereof relative to one another, as shown in FIG. 4A. More specifically,the reed switch(s) may be comprised of a switch 81 a disposed within oneof the shafts (e.g., shaft 12 a) and a magnetic element 81 b (e.g.,electromagnet, permanent magnet, coil, etc.) disposed within theopposing shaft (e.g., shaft 12 a) such that upon approximation of shafts12 a and 12 b, the reed switch 81 a is activated or closed by themagnetic field of the magnetic element 81 b and, likewise, as shafts 12a and 12 b are moved away from each other, the lack of magnetic fieldoperates to deactivate or open the reed switch 81 a. In this manner, theproximity of shafts 12 a and 12 b and thus, jaw members 110 and 120, maybe determined based on the reaction of the reed switch 81 a to themagnetic element 81 b.

Any of the above discussed sensors, switches, and/or strain gauge(s) maybe incorporated within an electrical circuit such that the straindetected by the strain gauge changes the electrical signal through thecircuit. With this purpose in mind, an electrical circuit between thestrain gauge and the switch 50 and/or an electrosurgical generator (notshown) allows communication of information such as desired tissuepressure thereto. This information may be tied to the activation ofswitch 50 such that the switch is not activated until a desired and/orpredetermined pressure on tissue grasped between jaw members 110 and 120is achieved as detected by the strain gauge. Accordingly, the straingauge may be disposed strategically on the forceps 10, e.g., on one ormore of jaw members 110, 120, such that pressure applied to tissuegrasped between jaw members 110 and 120 affects the strain gauge.

In use, forceps 10 may be calibrated such that particular tactileresponses (e.g., the first tactile response) of switch 50 corresponds toa predetermined grasping pressure on tissue as determined through use ofone or more of the above discussed sensors, switches, and/or straingauge(s). The predetermined grasping pressure about tissue is within therange of about 3 kg/cm2 to about 16 kg/cm2 in one embodiment and, inanother embodiment, about 7 kg/cm2 to about 13 kg/cm2. In someembodiments, switch 50 may generate multiple tactile responses, each ofwhich corresponds to different predetermined grasping force. For a moredetailed discussion of force sensing and/or measuring devices such asload cells, strain gauges, etc., reference is made to commonly-ownedU.S. application Ser. No. 11/409,154, filed on Apr. 21, 2006.

As shown in FIGS. 2, 4B, and 4C, the pivot 65 connects through anaperture 125 defined through jaw member 120 and matingly engages a pivotplate 66 seated within a circumferential lip or flange 78 (FIG. 4B)defined around the periphery of aperture 125 such that the pivot 65 isrotatably movable within the aperture 125 to move jaw members 110 and120 between open and closed positions.

In some embodiments, actuation of the knife 85 is associated withactivation of the switch 50. For example, sensor 87 may be embodied as aposition sensor configured to detect the position of knife 85 relativeto jaw members 110 and 120 and/or relative to tissue held therebetween.Additionally or alternatively, sensor 87 may be configured to detecteither of the first and second tactile responses of switch 50 and allowor prevent actuation of the knife 85 accordingly. For example, based onfeedback from the sensor 87, any one or more inter-cooperating elementsor lockout mechanisms associated with the actuating mechanism 40 may beenergized or de-energized to allow or prevent actuation of the knife 85,as described in more detail below.

As shown in FIG. 7, knife 85 includes a step 86 that reduces the profileof the knife 85 toward a distal end thereof. The distal end of the knife85 has a step 88 that increases the profile of the knife 85 toward asharpened distal cutting edge 89. The knife 85 includes a chamferedportion 84 where the sharpened distal cutting edge 89 meets the step 88to facilitate smooth retraction of knife 85 through the knife channel15.

In some embodiments, the forceps 10 may include a safety lockoutmechanism having a series of suitable inter-cooperating elements (e.g.,anti-deployment link 47, trigger link 47) that work together to preventunintentional firing of the knife 85 when the jaw members 110 and 120are disposed in the open position. Generally, the anti-deployment link47 mechanically cooperates with the trigger link 43 to preventadvancement of the knife 85 until the jaw members 110 and 120 are closedabout tissue. One such safety lockout mechanism for use with forceps 10is described in commonly-owned U.S. application Ser. No. 12/896,100entitled “Blade Deployment Mechanisms for Surgical Forceps”, filed onOct. 1, 2010.

In some embodiments, any one or more of the inter-cooperating elementsof the safety lockout mechanism (e.g., anti-deployment link 47) may beelectrically interconnected to the switch 50 and include suitableelectro-mechanical components (e.g., springs, rods, solenoids, etc.)configured to be energized via activation of the switch 50 (e.g., viaany one of leads 71 a, 71 b, 71 c, 71 d, 71 e) to mechanicallymanipulate the safety lockout mechanism. For example, upon electricalconduction through leads 71 d and 71 e to energize the end effector 100,the anti-deployment link 47 is energized to cause actuation thereof suchthat the safety lockout mechanism disengages to allow selectiveactuation of the knife 85. In this scenario, by way of example,selective actuation of the knife 85 may be prevented until switch 50 hasbeen depressed to generate at least the first tactile response.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

1-16. (canceled)
 17. A surgical forceps for treating tissue, comprising:a pair of shafts each having a jaw member disposed at a distal endthereof, each shaft of the pair of shafts configured to rotate about apivot to move the jaw members relative to each other; a knife configuredto cut tissue disposed between the jaw members; a trigger extending fromone of the shafts, the trigger operably coupled to the knife androtatable to actuate the knife to cut tissue disposed between the jawmembers; and an anti-deployment link disposed adjacent to the triggerand configured to engage the trigger to prevent rotation of the trigger.18. The surgical forceps according to claim 17, further comprising astop member disposed on at least one of the jaw members and configuredto control a distance between the jaw members.
 19. The surgical forcepsaccording to claim 17, further comprising an actuating mechanism housedwithin one of the shafts and operably coupled to the trigger, thetrigger rotatable to cause the actuating mechanism to actuate the knife.20. The surgical forceps according to claim 17, wherein approximation ofthe pair of shafts moves the anti-deployment link out of engagement withthe trigger to permit rotation of the trigger.
 21. The surgical forcepsaccording to claim 17, wherein the trigger includes a pair of handlemembers extending from opposing sides of one of the shafts.
 22. Asurgical forceps for treating tissue, comprising: a pair of shafts eachhaving a jaw member disposed at a distal end thereof and a handle at aproximal end thereof, each handle defining a fingerhole configured toreceive a finger of a user for rotating each shaft of the pair of shaftsabout a pivot to move the jaw members relative to each other; a knifeconfigured to cut tissue disposed between the jaw members; a triggerextending from one of the shafts at a location distal to the handles,the trigger operably coupled to the knife and rotatable to actuate theknife to cut tissue disposed between the jaw members; and ananti-deployment link disposed adjacent to the trigger and configured toengage the trigger at a location distal to the handles to preventrotation of the trigger.
 23. The surgical forceps according to claim 22,further comprising a stop member disposed on at least one of the jawmembers and configured to control a distance between the jaw members.24. The surgical forceps according to claim 22, further comprising anactuating mechanism housed within one of the shafts and operably coupledto the trigger, the trigger rotatable to cause the actuating mechanismto actuate the knife.
 25. The surgical forceps according to claim 22,wherein approximation of the pair of shafts moves the anti-deploymentlink out of engagement with the trigger to permit rotation of thetrigger.
 26. The surgical forceps according to claim 22, wherein thetrigger includes a pair of handle members extending from opposing sidesof one of the shafts.
 27. A surgical forceps for treating tissue,comprising: a pair of shafts each having a jaw member disposed at adistal end thereof and a handle at a proximal end thereof, each handledefining a fingerhole configured to receive a finger of a user forrotating each shaft of the pair of shafts about a pivot to move the jawmembers relative to each other; a knife configured to cut tissuedisposed between the jaw members; a trigger extending from one of theshafts at a location distal to the handles, the trigger operably coupledto the knife and rotatable to actuate the knife to cut tissue disposedbetween the jaw members; and an anti-deployment link disposed at alocation distal to the handles and configured to engage the trigger at alocation distal to the handles to prevent actuation of the knife. 28.The surgical forceps according to claim 27, further comprising a stopmember disposed on at least one of the jaw members and configured tocontrol a distance between the jaw members.
 29. The surgical forcepsaccording to claim 27, wherein approximation of the pair of shaft movesthe anti-deployment link out of engagement with the trigger to permitactuation of the knife.
 30. The surgical forceps according to claim 27,wherein the trigger includes a pair of handle members extending fromopposing sides of one of the shafts.
 31. The surgical forceps accordingto claim 27, further comprising an actuating mechanism housed within oneof the shafts and operably coupled to the trigger, the trigger rotatableto cause the actuating mechanism to actuate the knife.